ES2397374T3 - Cold box casting binder systems that have improved demoulding - Google Patents

Abstract

A foundry binder system, which will be cured in the presence of sulfur dioxide and a radical free radical initiator, comprising: (a) from 20 to 70 parts by weight of a cycloaliphatic epoxy resin or a mixed aliphatic-cycloaliphatic epoxy resin; (b) from 10 to 50 parts by weight of a monomeric acrylate monomer; and (c) an effective amount of peroxide, where (a), (b) and (c) are separate components or are mixed with others of said components, so that (b) is not mixed with (c), and where said parts by weight are based on 100 parts of binder.

Description

Cold box casting binder systems that have improved demoulding

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

5 STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO AN APPENDIX OF MICROFICHAS

Not applicable.

BACKGROUND OF THE INVENTION

10 (1) Field of the Invention

This invention relates to foundry binder systems, which will be cured in the presence of sulfur dioxide and a free radical initiator, comprising (a) an aliphatic epoxy resin; (b) a multifunctional acrylate; and (c) an effective amount of a free radical initiator. Casting binder systems are used to make foundry mixes. Casting mixtures are used to make foundry dies (such as males and

15 molds) that are used to make metal castings, particularly cast aluminum parts.

(2) Description of the Related Technique

In the foundry industry, one of the procedures used to make metal parts is "sand casting". In sand casting, disposable molds and males are manufactured with a mixture of sand and an organic or inorganic binder. Casting dies are arranged in a casting unit, which results in

20 a cavity in which molten metal is poured. The binder is needed so that the molds and the males do not disintegrate when they come into contact with the molten metal. After the molten metal is poured into the mold and male unit and cooled, the metal part formed by the process is removed from the unit.

Two of the outstanding manufacturing procedures used in sand casting are the uncooked and cold box procedures. In the uncooked process, a liquid curing catalyst is mixed with an aggregate.

25 and a binder to form a foundry mixture before forming the mixture into a model. The foundry mixture is shaped by putting it on a model and letting it cure until it is self-supporting and can be handled. In the cold box process, a gaseous curing catalyst is passed through a formed mixture (usually in a male box) of the aggregate and the binder to cure the mixture.

The male or mold produced from the binder must maintain its dimensional accuracy during the pouring of the

30 metal, but it must disintegrate after the metal cools, so that it can be easily separated from the metal part formed during the casting process. On the other hand, time-consuming and labor-intensive means must be used to decompose (unmold) the agglutinated sand, so that the metal part can be removed from the casting unit. This is a problem particularly with the internal males, which are fitted in the casting unit and are not easily removed. Usually, energy is applied

35 mechanical to the casting to facilitate removal. If the male does not decompose sufficiently during the solidification and cooling phase of the metal, the male is difficult to remove and requires excessive mechanical balotting to remove it, or in extreme cases it may require cooking at temperatures exceeding 425 ° C for prolonged periods. thermally degrade the male. This can result in substantial productivity losses as well as excessive energy use.

40 In iron or steel casting, the pouring temperature is typically around 1550 ° C. These high pouring temperatures facilitate the decomposition of the male. However, in the case of light metals such as aluminum, the decomposition of the male is hindered due to the relatively low pouring temperature of the metal. For example, aluminum is typically poured at a temperature of about 725 ° C. Not only does this lower pour temperature not facilitate the decomposition of the male, but the cast aluminum part is

45 cools more quickly than a cast iron piece of similar dimensions, so that the decomposition of the male during the cooling phase of the cast piece is not so facilitated. In view of these circumstances, the removal of males is a common problem in aluminum casting, there is a need for improved binders that produce males, which not only provide good males and castings, but result in a good removal of the males

U.S. Patent UU. 4,176,114 discloses a binder composition of poly (furfuryl alcohol), which is mixed in an aggregate together with an organic peroxide (preferably methyl ethyl ketone peroxide, MEKP). The mixture is shaped as a mold or male and gasified with sulfur dioxide. Sulfur dioxide is oxidized by peroxide and a strong acid is generated, which polymerizes poly (furfuryl alcohol) and hardens the mold. This binder is sold under the trade name "INSTADRAW". The binder provides males that are easy to remove from a cast aluminum part. In fact, the withdrawal times of the males are significantly shorter than when cold box binders of phenolic urethane are used to prepare the males.

However, the INSTADRAW binder has two disadvantages. First, when the binder was actually used in a foundry, a chemically resistant poly (furfuryl alcohol) coating was slowly deposited on the tools in the male box. This deposit was very difficult to remove and, if not removed periodically, the males would stick to the tools and the dimensional accuracy would be impaired. Second, the methyl-ethyl ketone peroxide free radical generator (MEKP) had to be handled as a separate part, and could only be transported in small containers. This constitutes a security risk if not handled properly. The MEKP catalyst was not stable to storage when combined with the poly (furfuryl alcohol) resin, and no other diluent for MEKP could be found that was compatible with the system. Although this system is still commercialized, its commercial development has been hampered by these disadvantages.

U.S. Patent UU. 4,518,723 discloses a binder, which is a mixture of an aromatic epoxy resin, such as bisphenol-A-epoxy, combined with a multifunctional acrylate, such as trimethylolpropane triacrylate (TMPTA), and cumene hydroperoxide. This composition is mixed with an inorganic aggregate, e.g. ex. sand, conforms and is gasified with sulfur dioxide. This use of this binder did not result in the formation of deposits on the tools of the male box during actual practice in a foundry, and was safer to use than the INSTADRAW binder because the cumene hydroperoxide could be diluted in the epoxy resin to form a storage stable solution. In addition, it forms males with a much greater tensile strength with a greater variety of inorganic aggregates. This binder system, known as ISOSET® binders, is commercially successful and is sold by Ashland Specialty Chemical Company. Although males made with ISOSET binders have a faster mold release in aluminum casting operations than phenolic urethane cold box binders, they do not have the rapid mold release characteristics of poly (furfuryl alcohol) binders. Therefore, there is a need for binders that produce males with the characteristics of rapid demoulding of males made with the polyfuryl alcohol binder, without sacrificing the tensile properties of the males, the productivity or the clean operating characteristics of the male. epoxy / acrylate system.

BRIEF SUMMARY OF THE INVENTION

Binders produce males, which decompose (demould) more easily and can be removed more quickly from the casting. This advantage is particularly important when castings are made of light metals. p. ex. aluminum. This improvement is obtained without damaging the traction properties of the male or productivity.

This improvement is very significant from a commercial point of view. The ability to remove the sand from the male of a cast in less time reinforces productivity and reduces labor costs, because, for most aluminum molding machines, the production bottleneck is withdrawal of the male

In addition, the quality of the castings is improved because all the sand from the males used to make the cast can be removed from the cast before use. Many casting operations, such as automobile and aerospace, cannot tolerate that even a single grain of sand remains in the casting. The binders of this invention produce males and molds that decompose easily, and allow the sand to be removed quickly and cleanly, not requiring drilling, sandblasting, dust brushing or high temperature postcooking.

Casting binders are used to make foundry mixes. Casting mixes are used to make cast dies, such as males and molds, which are used to make metal castings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Not applicable.

DETAILED DESCRIPTION OF THE INVENTION

The detailed description and examples will illustrate specific embodiments of the invention and allow a person skilled in the art to practice the invention, including the best mode. It is contemplated that many equivalent embodiments of the invention can be handled in addition to these specifically disclosed. All

5 units are in the metric system and all percentages with percentages by weight unless otherwise specified.

For the purpose of describing this invention, "aliphatic epoxy resin" includes a mixed cycloaliphatic or aliphatic cycloaliphatic epoxide having any aliphatic groups. The aliphatic epoxy resin may contain monomeric epoxy compounds mixed with polymeric epoxy compounds.

10 The most preferred aliphatic epoxy resins are represented by the following structural formulas:

where "n" 1 and "m" is an integer, typically 1 to 4, preferably 2-3, or

where "n" 1.

R 15 in structures I and II is predominantly aliphatic in nature, but may contain oxygen functionality as well as mixed aliphatic-aromatic groups. Typically, R is selected from the group consisting of alkyl groups, cycloalkyl groups, mixed alkyl-cycloaliphatic groups and substituted alkyl groups, cycloalkyl groups or alkyl-cycloaliphatic groups, where the substituents include, for example, ether, carbonyl and carboxyl groups.

The epoxy functionality of the epoxy resin may vary from 1.8 to 3.5, but typically it is equal to or greater than 2.0, more typically from 2.3 to 3.5. Particularly preferred are aliphatic epoxy resins having an average weight per epoxy group of 100 to 300, preferably 120 to 250.

Useful aliphatic epoxides include glycidyl ethers prepared from aliphatic polyols useful in this invention, including glycidyl ethers of trimethylolpropane, 1,4-butanediol, neopentyl glycol, bisphenol-A, hydrogenated cyclohexanedimethanol, sorbitol, glycerin, hexanodithol, penterenediol, peptide -bis (hydroxymethyl) tetrahydrofuran and the like. Glycidyl ethers of aliphatic polyols containing unsaturation, such as 2-butynediol, can also be used. Cycloaliphatic epoxy compounds that are useful include 3,4epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (ERL 4221 from Union Carbide), bis (3,4-epoxycyclohexylmethyl) adipate, 1,2-epoxy-4-vinylcyclohexane and the like. Also useful are epoxides prepared from epoxidation with peracids of

30 polyunsaturated hydrocarbons.

The free radical initiator (c) is a peroxide and / or hydroperoxide. Examples include ketone peroxides, peroxy ester free radical initiators, oxides, chlorates, perchlorates and alkyl perbenzoates. Preferably, however, the free radical initiator is a hydroperoxide or a mixture of peroxide and hydroperoxide. Particularly preferred hydroperoxides in the invention include t-butyl hydroperoxide, cumene hydroperoxide, paracetane hydroperoxide, etc. Organic peroxides can be peroxides

aromatic or alkyl. Examples of useful diacyl peroxides include benzoyl peroxide, lauroyl peroxide and decanoyl peroxide. Examples of alkyl peroxides include dicumyl peroxide and di-t-butyl peroxide.

Cumene hydroperoxide and / or a multifunctional acrylate, such as trimethylolpropane triacrylate, can be added to the epoxy resin before mixing it in the foundry aggregate. Optionally, a solvent can be added

or solvents to reduce the viscosity of the system or impart other properties to the binder system such as moisture resistance. Examples of solvents include aromatic hydrocarbon solvents, such as ocresol, benzene, toluene, xylene, ethylbenzene and naphthalenes; reactive epoxy diluents, such as glycidyl ether,

or an ester solvent, such as dioctyl adipate, rapeseed methyl ester, and the like, or mixtures thereof. If a solvent is used, sufficient solvent should be used so that the resulting viscosity of the epoxy resin component is less than 1,000 centipoise, preferably less than 400 centipoise.

The reactive unsaturated acrylic monomer or polymer or the mixture thereof (c) contains ethylenically unsaturated bonds. Examples of such materials include a variety of monofunctional, difunctional, trifunctional, tetrafunctional and pentafunctional monomeric acrylates and methacrylates. A representative list of these monomers includes alkyl acrylates, acrylated epoxy resins, cyanoalkyl acrylates, alkyl methacrylates, cyanoalkyl methacrylates and difunctional monomeric acrylates. Other acrylates, which can be used, include trimethylolpropane triacrylate, methacrylic acid and 2-ethylhexyl methacrylate.

Although solvents are not required for reactive unsaturated acrylic resin, they can be used. Typical solvents used are generally polar solvents, such as liquid dialkyl esters, e.g. ex. dialkyl phthalate of the type disclosed in US Pat. UU. 3,905,934, and other dialkyl esters such as dimethyl glutarate. Also useful are fatty acid methyl esters, particularly rapeseed methyl ester. Suitable aromatic solvents are benzene, toluene, xylene, ethylbenzene and mixtures thereof.

Although the components can be added to the foundry aggregate separately, it is preferable to combine the epoxy novolac resin and the free radical initiator as a Part I and add to the foundry aggregate first. The ethylenically unsaturated material, such as Part II, is then added to the foundry aggregate, either alone or together with some of the epoxy resin.

Typically, the amounts of the components used in the binder system are from 20 to 70 percent by weight of aliphatic epoxy resin, preferably from 50 to 60 percent by weight; from 10 to 25 percent by weight of free radical initiator, preferably from 15 to 20 percent by weight; and from 10 to 50 percent by weight of multifunctional acrylate, preferably from 15 to 35 percent by weight, where the percentage by weight is based on 100 parts of the binder system.

It will be apparent to those skilled in the art that other additives such as silanes, silicones, life extensions ("bench life"), release agents, defoamers, wetting agents, can be added to the aggregate, or the foundry mixture. etc. The particular additives chosen will depend on the specific purposes of the binder.

Various types of aggregate and amounts of binder are used to prepare foundry mixtures by methods known in the art. Normal matrices, precision casting matrices and refractory matrices can be prepared using the binder systems and the appropriate aggregate. The amount of binder and the type of aggregate used are known to those skilled in the art. The preferred aggregate used to prepare foundry mixtures is sand in which at least about 70 percent by weight, and preferably at least about 85 percent by weight, of the sand is silica. Other materials for aggregates suitable for normal foundry dies include zircon, olivine, aluminosilicate, chromite sands and the like.

In normal sand casting applications, the amount of binder is generally not more than about 10% by weight and is often within the range of about 0.5% to about 7% by weight based on the weight of the aggregate. Most often, the binder content for normal sand casting dies varies from about 0.6% to about 5% by weight based on the weight of the aggregate in normal sand casting dies.

The foundry mixture is molded into the desired conformation by tamping, blowing or other known methods for making male and foundry molds. Next, the model is cured almost instantaneously by the cold box process, using sulfur dioxide in the form of steam as the curing agent (most typically a combination of nitrogen, such as a carrier, and sulfur dioxide containing 35 weight percent to 65 weight percent sulfur dioxide), described in US Pat. UU. 4,526,219 and 4,518,723, which are hereby incorporated by reference. The shaped article is preferably exposed to effective catalytic amounts of sulfur dioxide in the form of 100 percent steam, although smaller amounts of a carrier gas can also be used. The exposure time of the sand mixture to the gas is typically 0.5 to 3 seconds. Although the smelting model is cured after gasification with sulfur dioxide, oven drying is necessary if the smelting model is coated with a refractory lining.

The male and / or the mold can be formed in one unit. Optionally, when casting pieces are made, the male and / or the mold can be coated with a water based refractory liner and subsequently dried. Next, the article is ready to be handled for further processing.

5 ABBREVIATIONS

The abbreviations used in the examples are as follows:

CHP cumene hydroperoxide (9.0% active oxygen).

BPA GE an aromatic epoxy resin derived from bisphenol-A and glycidyl ether, which has an approximate EEW of 188.

10 DOA dioctyl adipate, an ester solvent.

EEW epoxy equivalent weight.

EPALLOY 5000 is a cycloaliphatic epoxy resin, which is prepared by hydrogenating bisphenol-A glycidyl ether, manufactured by CVC Specialty Chemicals.

ERL-4221 an aliphatic epoxy resin, 3,4-epoxycyclohexylcarboxylate 3,4-epoxycyclohexanecarboxylate, manufactured by Union Carbide.

ERISYS GE-30 an aliphatic epoxy resin prepared by reacting trimethylolpropane and glycidyl ether, manufactured by CVC Specialty Chemicals.

HI-SOL 15 aromatic solvent.

RA release agent.

20 SCA silane coupling agent.

TMPTA trimethylolpropane triacrylate, an unsaturated monomer.

EXAMPLES

Although the invention has been described with reference to a preferred embodiment, those skilled in the art will understand that various changes can be made and the elements can be substituted for equivalents thereof without departing from the scope of the invention. In addition, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is understood that the invention is not limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments that are within the scope of the appended claims. In this application, all units are in the metric system

30 and all amounts and percentages are by weight, unless expressly stated otherwise.

The components of Part I and Part II of the binder were combined for 3 minutes using a Hobart sand mixer. Test males were prepared by adding 0.8 percent by weight of the binder (Part I was added first) to 2000 grams of Badger 5574 silica sand, so that the ratio of Part I / Part II was 1: 1, blowing the mixture at 2.76 bar (40 psi), using a Gaylord MTB-3 male blower unit,

35 by gassing with 50% sulfur dioxide in nitrogen for 1.5 seconds, and then purging with air for 10 seconds. "Dog bone" shaped males were used to test the tensile strengths of the males and "cuneiform" or "trapezoidal" males were used to test the demoulding of the males. Males were allowed to posture at room temperature for 24 hours before the test.

The base of the symmetric trapezoidal test male measures 10.2 cm (4 "), the height is 12.7 cm (5") and the top

40 is 4.4 cm (1.75 ") wide. The male has a uniform thickness of 3.8 cm (1.5"). Extending from the bottom plane and the top plane are two and one cylinders 2.5 cm (1 ") high with a diameter of 1.9 cm (0.75"), respectively. The separation of the cylinders that extend from the lower plane is 5.7 cm (2.25 "), from center to center. These" male footprints "hold the male in place in the mold, so that a wall thickness of the uniform casting piece of 0.6 cm (0.25 ").

The test males were used as internal males to make a cast aluminum piece. A test male was placed in the lower half of a sand mold designed for placement of the test male. Next, the upper half of the mold, which contained a channel through which metal could be poured, was inserted over the lower half.

5 Cast aluminum 319 having a temperature of 730 ° C was poured into the casting unit and then allowed to cool. The resulting cast aluminum piece was a hollow trapezoid that was 0.6 cm (0.25 ") thick. There is a 1.9 cm (0.75") hole in the center of the upper end face of the trapezoid. and two holes in the lower end face of the casting.

One face of the cast piece had a 2.5 cm x 2.5 cm x 2.5 cm (2 "x 2" x 2 ") block of metal protruding from

10 It is used to attach the cast aluminum part to the Herschal hammer during the demolding test. The demolding tests were carried out at room temperature (cold) by joining the cast aluminum part to a mechanical Herschal hammer of 2.76 bar (40 psi) to the projection in the trapezoidal casting test piece. The Herschal hammer applied pressure on the casting at intervals of 15 seconds until the inner tap was removed from the cast aluminum through the holes of the test plug. The amount of sand that comes out of the

15 cast piece from the hole of the 3.8 cm (1.5 ") face of the trapezoidal cast piece was measured every 15 seconds. The amount of sand poured from the bottom hole is calculated for each interval. The test it stops if all the male's sand is removed before 120 seconds.

Comparative Example A

(Use of an aromatic epoxy resin)

20 A two part binder system was prepared, described as follows.

Part I:

BPA GE 65%

CHP 35

Part II:

BPA GE 49.73%

TMPTA 42.32

Aromatic Solvent 3.5

Ester Solvent 3.5

0.4 release agent

Silane Coupling Agent 0.55

19.2 grams of Part I and 12.8 grams of Part II are added to 4000 grams of Badger 5574 silica sand. The components are mixed for 4 minutes in a Hobart mixer. The thoroughly mixed sand / resin mixture is then blown into a mold and gassed 1 second with 50/50 nitrogen / SO2, followed by a 10 second air purge. Then, the hardened male is removed and allowed to age for 24 hours. The

The tensile strength of the male at 24 hours was 9.10 bar (132 psi). Next, the male was introduced into a mold and poured into the cast aluminum unit at approximately 730 ° C. After 20 minutes, the cast aluminum part, which contains the inside of the partially decomposed male, is removed from the mold and placed on a Herschel agitator. The cast is weighed at the intervals indicated above, and the percentage of sand that remains in each interval is calculated. After 120 seconds, 85% of the sand was removed from the casting.

30 Example 1

(Use of aliphatic epoxy resin / Erisys GE-30)

A two part binder system was prepared, described as follows.

Part I:

Erisys GE-30 70% CHP 30

Part II:

TMPTA 50.0% Erisys GE-30 49.6 Silane A-187 0.4

16 grams of Part I and 16 grams of Part II were added to 4000 grams of Badger 5574 sand. A test male was prepared as in Example 1. Tensile strength after 24 hours was 8.82 bar ( 128 psi). The release properties of the male were tested as in Example 1. After 30 seconds, 100% of the

5 sand of the male had been unmold from the cast. In comparison, in Comparative Example A, only 40% of the sand was removed in 30 seconds.

Example 2 (Use of aliphatic epoxy resin / Epalloy 5000)

A two part binder was prepared.

Part I:

Epalloy 5000 65% CHP 35

Part II:

TMPTA 50.0% Erisys GE-30 49.6 Silane A-187 0.4

10 16 grams of Part I and 16 grams of Part II were added to 4000 grams of Badger 5574 sand. A test male was prepared as in Example 1. Tensile strength after 24 hours was 9.03 bar (131 psi). The test male was evaluated as in Example 1. In 5 seconds, 100% of the sand had been demoulded from the casting. In contrast, in Comparative Example A, only 8% of the sand was removed after 5 seconds. 15 Example 3 (Use of aliphatic epoxy resin / ERL 4221)

A two part binder system was prepared.

Part I:

ERL 4221 70% CHP 30

(continuation)

Part II:

TMPTA 49.40%

Epalloy 5000 25.

ERL 4221 25

Silane A-187 0.6

16 grams of Part I and 16 grams of Part II were mixed in 4000 grams of Badger 5574 sand. A test male was prepared as in Example 1 and evaluated as previously described. Tensile strength 5 after 24 hours was 9.52 bar (138 psi). In 30 seconds, 100% of the sand was removed from the casting.

Comparative Example B

(Comparison with a commercial binder)

A two-part amine cured phenolic urethane cold box system was evaluated. This system, known as ISOCURE® 393N / 693N binder (sold by Ashland Specialty Chemicals, a division of Ashland Inc.), was specifically designed for aluminum applications and is considered to be one of the best amine cured systems for this purpose. .

In a mixer, 17.6 grams of ISOCURE® 393 and 14.4 grams of ISOCURE® 693 were added to 4000 grams of Badger 5574 sand. The sand was thoroughly mixed and the mixture was blown into the mold as previously described, but 1.5 seconds is gasified with a triethylamine / air stream. A test male was prepared as in the

Example 1 and was evaluated as previously described. Tensile strength after 24 hours was 10.34 bar (150 psi). After 120 seconds, 94% of the sand was removed.

Table I summarizes the data of the tensile tests and the demolding tests performed on males made from the binders of Comparative Examples A and B, and Examples 1-3.

Table I (Summary of data related to the time to unmold 100% of the sand from the test piece 20)

Example

Tensile Strength [bar (psi)] after 24 hours Release Time (seconds)

TO

9.10 (132) > 120 (only 85% of the sand unmoulded after 120 seconds)

one

8.83 (128) 30

2

9.03 (131) 5

3

9.52 (138) 30

B

10.34 (150) > 120 (only 94% of the sand was removed after 120 seconds)

The data in Table I clearly show the improvement in male demoulding, which results when an aliphatic epoxy resin is used to formulate the binder. This improvement is very significant from a commercial point of view. The ability to remove the sand from the male of a cast piece in less than 1/10 of the time now

25 required with current technology is of enormous importance, particularly with regard to the casting of aluminum parts. Time and labor are significantly reduced, reinforcing productivity, because, for most aluminum molding machines, the bottleneck is the time of demolding.

In addition, the quality of the castings is greatly improved because all the sand from the males used to make the cast can be removed from the cast before use. Many 30 casting applications, such as automotive and aerospace, have very strict and low tolerances for residual sand.

in the cast piece. The binders of this invention produce males and molds that decompose easily, and allow the sand to be removed quickly and cleanly, not requiring drilling, sandblasting, polishing or postcooling at high temperatures.

Claims (9)

1. A foundry binder system, which will be cured in the presence of sulfur dioxide and a free radical initiator, comprising: (a) from 20 to 70 parts by weight of a cycloaliphatic epoxy resin or a mixed aliphatic-cycloaliphatic epoxy resin;

(b)

 from 10 to 50 parts by weight of a monomeric acrylate monomer; Y

(C)

 an effective amount of peroxide,

where (a), (b) and (c) are separate components or are mixed with other of said components, provided that (b) is not mixed with (c), and where said parts by weight are based on 100 parts of binder. The binder system according to claim 1, wherein the epoxy resin comprises an epoxy resin represented by the following structural formula: where n 1 and m is an integer from 1 to 4. 3. The binder system according to claim 1, wherein the epoxy resin comprises an epoxy resin 15 represented by the following structural formula: where "R" is a predominantly aliphatic substituent and where n 1. 4. The binder system according to claim 2 or 3, wherein the epoxy resin has an epoxide equivalent weight of about 100 to about 300.

The binder system according to claim 4, wherein the acrylate is a monomer and the monomer is trimethylolpropane triacrylate and the peroxide is a hydroperoxide.

6.

 The binder system according to claim 5, wherein the hydroperoxide is cumene hydroperoxide.

7.

 The binder system according to claim 1, wherein the monomeric acrylate monomer is a difunctional, trifunctional, tetrafunctional or pentafunctional acrylate / methacrylate.

25 8. A foundry mixture comprising:

(to)

 a major amount of foundry aggregate;

(b)

 an effective binder amount of the casting binder system according to any one of claims 1 to

6. 9. A cold box method for preparing a casting model comprising: (a) introducing the casting mix according to claim 8 into a model; Y (b) cure with gaseous sulfur dioxide.

10.

 A foundry die obtainable by the method according to claim 9.

eleven.

 A method for casting a metallic article comprising:

(to)

 manufacturing an uncoated cast iron matrix according to the method of claim 9;

(b)

 pouring said metal while in a liquid state in said coated cast iron matrix; Y

(C)

 allow said metal to cool and solidify; Y

(d)

 Then separate the molded article.